不同黑麦草及其近缘种高羊茅的RAPD多态性分析

利用RAPD分子标记技术对黑麦草及其近缘种高羊茅的遗传关系进行了分析,结果发现,14个引物共扩增出62条带,其中52条带为多态性带,占总带数的83.9%,表明在这8个品种间具有较高的遗传多样性,存在一定的遗传分化。从UPGMA聚类分析的结果来看,特高黑麦草、蓝天堂黑麦草、多年生黑麦草、羊毛黑麦草、邦德黑麦草、美兰黑麦草和高羊茅黑麦草作为一个系谱群,它们之间有较为密切的亲缘关系;同时发现,高羊茅与其它7个草种间存在有较明显的遗传分化。     

赤霉素和硝酸钾对高羊茅四个品种发芽的影响

本文研究了赤霉素与硝酸钾不同浓度浸种对高羊茅四个品种发芽的影响。分析结果表明：高羊茅品种在发芽试验中起主要作用。硝酸钾在０．１％－０．３％浓度范围内,对高羊茅四个品种的发芽起抑制作用。赤霉素对高羊茅四个品种发芽起促进作用,其中以０．２ｍｇ／Ｌ浓度较为理想。     

高羊茅种子产量因子与产量的通径分析

采用多因素正交试验设计,通过大样本相关、通径和逐步回归分析后表明,高羊茅5个种子产量因子对种子产量的直接贡献大小排序为:生植枝数/m2＞小花数/小穗＞种子粒数/小穗＞单粒种子重＞小穗数/生植枝;提高小花数/小穗和种子粒数/小穗可最有效提高高羊茅的种子产量,其次是提高生植枝数/m2.     

NaCl对高羊茅萌发的胁迫效应研究

通过室内模拟盐胁迫对高羊茅不同品种萌发的胁迫效应研究,揭示单盐对牧草、草坪草种子萌发活力的影响和萌发盐分临界值,以期为盐碱地改良和优良牧草的引选提供依据;用不同浓度NaCl作为高羊茅萌发培养液,通过测定相对发芽率并对其进行回归分析;结果表明,NaCl盐胁迫对高羊茅种子的萌发有抑制作用,且在0～0.6%的低盐浓度范围内抑制作用不明显,NaCl盐浓度高于0.6%时抑制作用显著;0.4%、0.6%、1.2%的NaCl浓度是高羊茅相对发芽率变化的几个"拐点"(即敏感点);高羊茅相对发芽率与盐浓度呈极显著负相关,Y=101.75-47.371 x,r=-0.98;14个品种中萌发期较耐盐的品种有佛浪、爆发力和翠碧A,火凤凰、交战2和火凰RT耐盐性较差;高羊茅萌发阶段进行耐盐性评价时,相对发芽率和耐盐半致死浓度是很好的萌发能力的鉴定指标,可以作为种子耐盐能力评价指标,但耐盐致死浓度不宜作鉴定指标.     

贮藏温度和种子含水量对高羊茅种子活力的影响

以高羊茅种子为试验材料,研究不同贮藏温度和种子含水量对高羊茅种子活力的影响.结果表明,贮藏温度和种子含水量均能影响高羊茅种子活力;随着贮藏时期的延长,高羊茅种子的活力呈下降趋势;贮藏温度为-15～15℃之间的种子发芽率、发芽指数、活力指数都较高;经过超干处理的高羊茅种子在不同含水量(1.77%～8.11%)之间时,发芽率、发芽指数、活力指数、苗重等指标差异不显著.     

高羊茅种子产量与主要农艺性状的通径分析

对高羊茅的7个农艺性状与单株种子产量进行了相关和通径分析.结果表明,7个农艺性状与单株种子产量均呈极显著正相关,其相关系数大小依次为单株穗数＞每穗粒数＞穗长＞千粒重＞茎重＞株高》叶片重.7个性状与单椿种子产量直接通径系数大小依次为叶片重＞株高＞单株有效穗数＞每穗粒数＞千粒重＞茎重＞穗长.叶片重、单株有效穗数和每穗粒对种子产量的贡献较大,茎重和穗长的效应较小,提高单株种子产量,要增加单株有效穗数和每穗粒数,并兼顾千粒重的提高.     

几种钠盐对高羊茅种子发芽的影响

研究了高羊茅种子在不同钠盐(NaCl、NaHCO3 Na2 CO3、Na2 SO4)溶液中的萌发情况.结果表明:当NaCl和NaHCO3浓度≤0.6％、Na2CO3浓度≤0.3％、Na2 SO4浓度≤0.9％时,高羊茅种子可正常萌发.NaCl和Na2SO4浓度≤0.3％、Na2 CO3和NaHCO3浓度≤0.1％时,对根长无抑制作用.NaCl、NaHCO3和Na2SO4浓度≤0.1％时,对芽长无抑制作用;Na2 CO3各浓度对芽长均有抑制作用.NaCl和NaHCO3浓度≤0.1％时对各项发芽指标均无显著影响.     

高羊茅高效组织培养再生体系的建立

植物分子育种与基因功能鉴定是建立在高效的组织培养再生体系基础上的。本研究以高羊茅(Festuca arundinacea Schreb)为材料,探讨了不同外植体状态、基本培养基类型、外源激素组合与固化剂种类与浓度对愈伤组织诱导的影响,并进行了愈伤组织分化长芽与生根研究。结果表明:愈伤组织诱导过程中,离体成熟胚比完整种子作外植体愈伤组织出现早、质量优、诱导率高;基本培养基的选择上以N6诱导率最高,MS最低;激素组合研究中高羊茅三个品种(SAFari, FirewarⅡ, Barleduc)在无6-BA培养基中,生长激素选择上都是2,4-D优于IAA,2~2.5 mg/L 2,4-D在三个品种中诱导率都在50%以上,而在添加0.5 mg/L 6-BA时诱导率都偏低;固化剂选择上则以Phytagel与Agarose二都最优,Phytagel固化剂最佳诱导浓度为2~4 g/L。分化长芽最佳培养基为MS+0.1 mg/L 2,4-D+0.1 mg/L 6-BA+0.5 mg/L NAA+20 mg/L AgNO3+2%蔗糖+0.6%琼脂,生根壮苗最佳培养基为1/2MS+0.5 mg/L NAA+3%蔗糖+0.3%Phytagel。本研究为高羊茅的高效转基因体系建立与CRISPR基因功能研究提供准备。     

几种化学物质和温度处理对高羊茅种子发芽的影响

用高羊茅(Festuca arundinacea)种子为试验材料,置入光照培养箱培养,研究化学物质和温度处理对其发芽的影响.结果表明:0.2%的次氯酸钠(NaClO)处理促进高羊茅种子的发芽,浓度梯度设置在0.5%～1.5%时均抑制其发芽,且浓度与发芽率和发芽势均成负相关.不同浓度的硝酸钾(KNO3)处理均促进其发芽,且浓度为2.0%时,发芽率最高,发芽势是先降低后升高.高羊茅最适播种温度为20℃,高于或低于20℃,对种子的发芽均有不同程度的抑制作用.     

Androgenesis from a Lolium multiflorum × Festuca arundinacea hybrid to generate extreme variation for freezing-tolerance

New opportunities for plant breeding using androgenesis in Lolium × Festuca hybrids have been identified. Plants derived by anther culture from a Lolium multiflorum × Festuca arundinacea (5x) hybrid were screened for freezing-tolerance, and their post-freezing recovery compared. The androgenic population showed extreme diversity in freezing-tolerance. While the majority of androgenic plants had inferior freezing-tolerance compared with the freezing-sensitive L. multiflorum parent, 6% of the population were more freezing resistant than the freezing-tolerant Festuca parent. Novel Lolium and Festuca gene combinations resulting from rare meiotic events were recovered within the androgenic population. The two most freezing-tolerant androgenic plants carried virtually the entire F. pratensis subgenome of F. arundinacea. F. pratensis is known to carry genes for freezing-tolerance and would be expected to be the primary source of genes governing this trait within the F. arundinacea genome. The most freezing-tolerant androgenic plants were more freezing-tolerant than the hybrid plant from which they were derived. Consequently, androgenesis was also effective in removing factor(s) reducing the expression of freezing-tolerance within the L. multiflorum × F. arundinacea (5x) hybrid.     

Introgression of crown rust resistance from Festuca spp. into Lolium multiflorum

Crown rust, Puccinia coronata Corda, causes one of the most damaging foliar diseases in Italian ryegrass, Lolium multiflorum Lam. For introgression of crown rust resistance, highly resistant hybrids of the crosses Festuca arundinacea (2n = 6x = 42) ×L. multiflorum (2n = 4x = 28) and reciprocally, L. multiflorum (2n = 2x = 14) ×Festuca pratensis (2n = 4x = 28) and subsequently resistant recombinant individuals were used as female parents and susceptible cultivars of Italian ryegrass as male parents in three successive backcrosses. The BC₃ plants were selfed and crossed mutually. Uredospores of seven different crown rust isolates collected from plants of L. multiflorum, Lolium perenne, F. pratensis, F. arundinacea and L. multiflorum × F. pratensis hybrids were applied to identify the resistance or susceptibility of the parental species, backcrossed, selfed and intercrossed progenies. The various crown rust populations revealed a species-specific capability to infect plants of the Lolium-Festuca complex corresponding to the host species from which the spores originated. Selected BC⁹ plants, however, were found to be completely resistant to all crown rust populations tested. Successful introgression of the resistance was achieved from F. arundinacea as well as from F. pratensis. The resistance represents a dominant character, apparently based on a strong heterologous incompatibility between host and pathogen. In phenotype, bivalent formation during meiosis and in fertility, the novel germplasms are comparable with the L. multiflorum cultivars.     

Cytogenetic Studies of Hybrids between Festuca gigantea Vill. and Lolium multiflorum Lam.

The meiotic behaviour of the hybrid between Festuca gigantea (2n – 6x = 42) and Festuca gigantea (2n = 6x = 42) indicates distinct structural differences between the two species. These differences are also apparent in the degree of chromosome pairing observed in Lolium multiflorum×F. gigantea compared with previous reports on the L. multiflorum×F. arundinacea hybrids. Although the L. multiflorum×F. gigantea 8x amphiploid com Dines the complementary characters of the two species and is agronomically interesting, there are some irregularities in meiotic behaviour that could affect the stability of the amphiploid. Seed fertility in the amphiploid is high and preliminary studies show evidence of a high degree of self-fertility. The pentaploid hybrid between autotetraploid L. multiflorum×F. gigantea is sufficiently fertile to be used as the pollen plant in crosses with diploid L. multiflorum (BC₁). Backcrossing the BC₃ hybrid to L. multiflorum results in mainly diploid progeny. The possibilities, of using this crossing scheme to introgress F. gigantea characters into L. multiflorum is discussed as an alternative approach to amphiploid breeding as a means o: combining specific complementary characters of the two species.     

Cytogenetic Studies of Crosses between Lolium multiflorum Lam. and Festuca arundinacea Schreb. III. The Generations C1, C2 and C3

Meiotic observations of 56-chromosome plants of the C₁, C₂ and C₃ generations of the amphidiploid Lolium multiflorum × Festuca arundinacea showed that most of the chromosomes paired as bivalents. However, uni- and multivalents were frequently observed. No difference in meiotic regularity and stability could be detected between the different generations. The average chromosome number and; the percentage of 56-chromosome plants decreased with increasing generations. The direct use of the 56-chromosome amphidiploids of L. multiflorum and F. arundinacea in a breeding programme appears to be quite difficult, but these plants can be used in a backcross programme with Lolium and Festuca.     

The controlled introgression of Festuca arundinacea genes into Lolium multiflorum

Summary Using phosphoglucoisomerase (PGI/2) as a genetic marker, it has been shown to be possible to transfer genes from Festuca arundinacea into diploid Lolium multiflorum using the pentaploid hybrid L. multiflorum (4x) x F. arundinacea (6x). The pentaploid hybrid was sufficiently fertile to be used in reciprocal crosses with diploid. L. multiflorum. When used as the male parent, only two backcross generations were then required to reconstitute the diploid genotype. Intergeneric recombinants including a F. arundinacea PGI/2 allele were found among the diploid BC₂. Cytological data indicates that although the majority of chromosome associations involve only homologous Lolium chromosomes, associations involving Lolium and Festuca chromosomes also occur.Interpollinating the pentaploid hybrids prior to commencing a backcrossing programme increases the number of cycles of recombination and improves the chance of recovering intergeneric recombinants. The crossing programme described is proposed to be an effective method of introducing F. arundinacea genes into L. multiflorum.     

Genomic structure of androgenic progeny of pentaploid hybrids, Festuca arundinacea × Lolium multiflorum

To assess the usefulness of the doubled haploid (DH) method in the breeding of forage grasses, a sample of anther-derived progeny of pentaploid F₁ hybrids of Festuca arundinacea × Lolium multifiorum was karyotyped using genomic in situ hybridization (GISH). The technique allowed scoring of the total number of chromosomes, the number of chromosomes contributed by each parent, and the number and positions of the Festuca-Lolium translocation breakpoints. Among 27 plants analysed, 13 belonged to three clones, effectively reducing the number of different progeny karyotyped to 17. These included 10 haploids, five doubled haploids and two plants for which the origins could not be explained. In all plants analysed, a mixture of chromosomes of both parents was present, including an average of 1.88 intergeneric translocations per plant. The translocation breakpoints were distributed along almost the entire length of the chromosome arms. Chromosome variation among androgenic progeny appeared much wider than that in the conventional backcross but low vigour and high mortality suggest that this additional variation may be difficult to exploit directly in breeding. However, a change in the pattern of recombination makes the entire genome accessible to manipulation.     

Unreduced gamete in interspecific hybrids in the Festuca/Lolium complex

Self-sterile interspecific hybrids between diploid Lolium perenne and either Festuca arundinacea or F. gigantea (both hexaploids) set some seeds when subjected to a heavy pollen cloud from the amphiploids derived from the hybrids. All the progeny were octoploid and were formed from the fertilization of unreduced gametes in the F₁ hybrid by amphiploid pollen. The significance of the results in relation to breeding efforts within the Lolium/Festuca complex is discussed.     

Habitat and management affect genetic structure of Festuca pratensis but not Lolium multiflorum ecotype populations

Genetic diversity present in permanent grassland may be valuable for broadening gene pools in breeding programmes and for conservation of genetic resources. However, little is known about the amount of genetic diversity present at specific habitats and about site‐related factors affecting it. To identify valuable habitats, genetic diversity of 12 ecotype populations and four reference cultivars of both Festuca pratensis Huds. and Lolium multiflorum Lam. was analysed using Simple sequence repeat markers (SSR). Analysis of molecular variance revealed a larger within population variation for L. multiflorum (97.1%) than for F. pratensis (92.6%). F. pratensis ecotype populations were clearly separated from cultivars and formed three distinct subclusters according to the geographic regions they were sampled from. Differences between L. multiflorum ecotype populations and cultivars were small and no grouping of populations was observed. Thus, only F. pratensis ecotype populations were structured and habitat as well as management had a slight influence on genetic structure. This information may allow the design of individual strategies for targeted utilization of genetic resources in plant breeding programmes.     

多花黑麦草不同品种草产量研究

本课题的总体目标是以区域试验和示范带动我国草种子的产业化生产,大幅度提高我国单位面积牧草及生态草种子的产量和质量,促进草种产业的起步与发展。对14个多花黑麦草品种进行品种比较试验,通过对参试品种物候期的观测、不同品种黑麦草鲜干草产量的测定及各品种不同时期刈割产量比较的研究,发现参试的十四个品种在本地区差异较为明显,从测定的各品种的各个数据来看,其中钻石T、海湾、特高表现较为突出,在生长势和产草量方面优于其它品种。故最适宜我区种植的多花黑麦草品种为钻石T、海湾、特高。